Subject: [Sigtran] SCON in response to DAUD

From: "Soni Goel" <[email-masked]>
Date: Tue, 6 Sep 2005 00:11:03 -0700

Hi,

This is regarding Section 4.5.3 ASP Auditing in draft RFC3332bis. As I
understand, this draft replaces the Implementor's Guide, Version 7.

The Implmentor's Guide, Version 7 proposed following change in the above
Section specifying that in response to DAUD message where the SGP
maintains the congestion status of the SS7 destination, the SGP MUST
additionally respond with an SCON message before the DAVA or DRST
message . 

This change is not present in the latest draft RFC3332bis. Can somebody
let me know if there is a specific reason for this? 

As per draft-ietf-sigtran-m3ua-implementors-guide-07.txt -
--------------------------------------------------------

3.8 Auditing procedure and congestion state
3.8.1 Description of the problem

   The current description of the AUDIT procedure in regards to
   congestion state is not clear enough. When to send SCON is not
   completely specified.

3.8.2 Text changes to the document
....
New text: (Section 3.3.1)
---------
 
   [...]. Where the SGP maintains the congestion status of the SS7
   destination, the SGP MUST additionally respond with an SCON message
   before the DAVA or DRST message.  If the SS7 destination is
   available, the SGP MUST respond with an SCON message (indicating the
   appropriate congestion level) and then a DAVA message.  If the SS7
   destination is restricted, the SGP MUST respond with an SCON message
   (with the appropriate congestion level) immediately followed by a
   DRST message.  If the SGP has no information on the availability
   status of the SS7 destination, the SGP responds with a DUNA message,
   as it has no routing information to allow it to route traffic to this
   destination.
 
   Where the SGP does not maintain the congestion status of the SS7
   destination, the response to a DAUD message should always be only a
   DAVA, DRST or DUNA message as appropriate.
--------------------------

Thanks,
Soni

---
Outgoing mail is certified Virus Free.
Checked by AVG anti-virus system (http://www.grisoft.com).
Version: 6.0.859 / Virus Database: 585 - Release Date: 2/14/2005

_______________________________________________
Sigtran mailing list
[email-masked]
https://www1.ietf.org/mailman/listinfo/sigtran

---

From: "Brian F. G. Bidulock" <[email-masked]>
Date: Tue, 6 Sep 2005 02:31:20 -0600

Soni,

I requested at last call that this section be corrected and was told by
the Editor: "Alternative text based on consensus provided."

I pointed out that the "[a]lternate text is in error.  This has been
discussed and no objections remain to the proposed text.  Please apply."

But, it fell on deaf ears; even though all discussions have come back to
the text that you cite at the bottom of your note.

Perhaps the Editor can point to the discussion that shows the consensus
upon which he based his deviation from that text.  (Although I doubt it
because it was consensus, after much discussion, that agreed on the
change in the first place.)

Unfortunately, it is not the only such occurrence in the draft.

What is clear of the matter is that the SCON MUST be sent before a DAVA
or a DRST (but rfc3332bis-04 does not require this) otherwise during
restart M3UA at the ASP cannot possibly know how long to wait for a
possibly trailing SCON before starting traffic.

Also, it is clear that unless the SGP maintains congestion state (in
accordance with whatever prevailing SS7 standards are applicable) it is
incapable of sending SCON, and can only therefore be required to send it
when it maintains it (but rfc3332bis-04 merely make a vague reference to
some sort of national network).

So, I would say it is a clear error in rfc3332bis-04, but, then, I
already said that at Last Call and was overruled by the Editor, and so
the document stands in error.

I would suggest following the text the you cite from IG-07 instead, for
the sake of interoperability and a functioning protocol.

See topic "M3UAbis - consensus on comment resolution" on the mail
archive for a longer list of problems with rfc3332bis-04.

--brian

Soni Goel wrote:                                                                       (Tue, 06 Sep 2005 00:11:03)

-- 
Brian F. G. Bidulock
[email-masked]
http://www.openss7.org/